Best Sprite Editor?

Hey I'm looking for a good, easy to use, and free if possible, because I dont want trouble sprite editor. The sprites are for a 2D game I want to make, and a sprite is limited to 256 colors and are small units and look ok at a distance. They let you edit pixel by pixel and do effects. I'm looking for one of these, and help would be nice.

I dont think its a native windows app, so it may give problems depending on your graphics card, resolution etc. If your having trouble with it have a look at one of the others in the other link to programmers heaven.